Neisseria gonorrhoeae, an obligate human pathogen, causes a common sexually transmitted infection, gonorrhea. While gonococci (GC) cause symptomatic inflammation of the genital tissue in men, GC infections in women are often asymptomatic. The silent infection allows the bacteria to disseminate, which can lead to pelvic inflammatory disease (PID), a leading cause of ectopic pregnancy and infertility. Disseminated gonococcal infection (DGI) may give rise to septic arthritis. Pregnant women can transmit the infection to newborns, causing blindness. Furthermore, silent GC infections increase the susceptibility of patients to HIV. These complications clearly make gonorrhea a significant public health problem, particularly in women. Our long-term goal is to delineate the cellular and molecular mechanisms underlying GC infections in women. The research on the mechanistic basis of GC infection in the female reproductive tract has been hindered by a lack of effective research models. Previous studies have mainly relied on nonpolarized epithelial cells. Because the surface of the female reproductive tract is protected by a layer of polarized epithelial cells, these data can only be applicable to clinical infections f GC interacts with polarized and nonpolarized epithelial cells in the same manner. The central hypothesis to be tested in this proposal is that GC interactions with polarized epithelial cells differ significantly from GC interactions with nonpolarized cells. We have formulated this hypothesis based on our strong preliminary data that show that the actin cytoskeleton is excluded from GC adherent sites at the apical surface of polarized epithelial cells, rather than being recruited to the adherent sites as seen in nonpolarized cells. The goal of this proposal is to define the differences between GC interactions with polarized and nonpolarized endocervical epithelial cells and to investigate the mechanistic links between the unique interaction of GC with the polarized cells and GC infection. To reach this goal, we will use polarized primary and virally immortalized human endocervical epithelial cells to pursue two aims: 1) to examine the nature of GC interactions with polarized endocervical epithelial cells and 2) to investigate how the unique interactions of GC with polarized endocervical epithelia lead to GC infection. Polarized primary and virally immortalized endocervical epithelial cell models will enable us to examine GC-epithelia interactions under the conditions that mimic the in vivo conditions of the female reproductive tract and to discover novel mechanisms that are specific for GC infections in women. Our strong preliminary studies demonstrate the potential of the proposed studies to expand the existing paradigms of GC infections. New mechanistic knowledge derived from the proposed studies will help to generate new strategies for interventions and therapies for gonorrhea and other sexually transmitted infections